Zeolitic catalytic cracking catalysts

ABSTRACT

There is provided a method for increasing the catalytic cracking activity, selectivity and attrition resistance of a crystalline aluminosilicate containing catalytic cracking catalyst by treating the catalyst at a temperature above about 1300*F. and below the thermal destructive temperature of the crystalline aluminosilicate in the absence of steam. The above treatment provides an improved catalytic cracking catalyst for utilization in the cracking of a hydrocarbon charge under catalytic cracking conditions.

United States atent Nelson et a1.

ZEOLITIC CATALYTIC CRACKING CATALYSTS Inventors: Gerald V. Nelson,Nederland;

Douglas J. Youngblood, Groves; James H. Colvert, Port Arthur, all ofTex.

Assignee: Texaco Inc., New York, N.Y.

Filed: Apr. 27, 1970 Appl. No; 29,758

Rielated US. Application Data Continu' ation of Ser. No. 717,968, April1, 1968, abandorled.

US. Cl. 252/455 Z; 208/120 Int. CL, B01J 29/06 Field oil Search 252/455Z References Cited UNITED STATES PATENTS Kimberlin, Jr. et al. 252/455 ZDec. 30, 1975 3,325,397 6/1967 Plank et al 252/455 X 3,329,628 7/1967Gladrow et al. 252/455 X 3,449,070 6/1969 McDaniel et al 252/455 Z3,518,051 6/1970 Maher et al 252/455 Z 3,553,104 1/1971 Stover et al....252/455 Z Primary Examiner-Carl F. Dees Attorney, Agent, or FirmThomasH. Whaley; Carl G. Ries 57 ABSTRACT 26 Claims, No Drawings ZEOLITICCATALYTIC CRACKING CATALYSTS This is a continuation of application Ser.No. 717,968, filed Apr. 1, 1968, now abandoned.

This invention relates to improved catalytic compositions and to theconversion of hydrocarbon oils employing such cata1ysts. In particular,this invention relates to improved zeolitic catalytic cracking catalystspossessing superior activity, selectivity and attrition resistance. Thisinvention further relates to a method for preparing improved catalyticcracking catalysts and to hydrocarbon conversion processes employingsuch catalysts wherein heavier petroleum fractions are cracked tolighter materials predominantly in the gasoline boiling range.

The cracking of heavier petroleum fractions into lighter and morevaluable constituents has previously been accomplished by the use ofelevated temperatures customarily referred to as thermal cracking. Inmore recent times the cracking process for producing lighter and morevaluable hydrocarbons, such as gasoline, has been the catalytic crackingmethod wherein numerous materials both natural and synthetic have beenemployed as catalysts. While the ability to facilitate cracking of thehydrocarbon in and of itself is significant, the catalyst mustadditionally possessother desirable characteristics such as the abilityto convert a given charge stock to a variety of desired and preselectedproducts under particular conditions of temperature, pressure and spacerate, normally termed activity. [If addition to activity, the catalystmust provide selectivity, i.e., the ability to convert the charge stockinto desired products with minimal by-product formation, as, forexample, providing high gasoline yields along with low gas and low cokeyields. A thirdhighly important catalyst characteristic is its abilityto withstand attrition over a period of continuous handling andregeneration. Catalysts possessing poor attrition resistance soon abradeand fragment giving rise to excessive amounts of finely divided materialwhich are generally unusable in conventional catalytic equipment andconsequently deleterious to the process and processing equipment.

More recently, manufacturers of catalytic cracking catalysts andhydrocarbon conversion processors have suggested that the activity,selectivity and attrition resistance of crystalline zeolitic catalystscould be improved by conditioning the catalyst in the presence of steamat elevated temperatures from about 500F. and higher. Further, afteremploying the catalyst in a hydrocarbon conversion process thecarbonaceous deposit laid down on the catalyst commonly referred to ascoke, was removed through a regeneration cycle at elevated temperaturesalso in the presence of steam. While the combination of steam and heatprovided the catalytic material with acceptable commercial levels ofactivity, selectivity and attrition resistance, such levels of catalyticproperties left great room for improvement.

It is therefore an object of this invention to provide an improvedcatalytic composition possessing superior activity, selectivity andattrition resistance.

Another object of this invention is to provide .a method for thepreparation of catalytic materials possessing superior activity,selectivityand attrition resistance.

A further object of this invention is to provide a hydrocarbonconversion process employing improved catalytic cracking catalysts.

Other objects 'andadvantages will'become apparent from the followingdetailed-descriptionand examples.

Broadly, this invention contemplates a method'for increasing thecatalytic cracking activity, selectivity and attrition resistance of acrystalline aluminosilicate containing catalytic cracking'cataly stwhich comprises treating said'catalyst at a temperature above aboutl300F. and below the thermal destructive temperature of the crystallinealuminosilicate contained therein.

In another embodiment, there is contemplated an improved catalyticcracking catalyst containing acrystalline aluminosilicate, where thecatalyst is characterized by enhanced activity, selectivity andattrition resistance, by treating a zeolitic cracking catalyst at atemperature above about 1300F. and below the thermal destructivetemperature of the zeolite contained therein.

uniform pore diameters ranging from about 4 to about 15 Angstrom units,generally referred to in the art as zeolites. Catalytic crackingzeolites because of their extremely high activity are composited with amaterial possessing lower catalytic activity as, for example, asilica-alumina matrix which may be of the synthetic, semi-synthetic ornatural clay type. Alternatively silica gel, silica-beryllia,silica-magnesia, silica'thoria, silicat itania and silica-zirconia maybe employed in place of silica-alumina. Preferably, materials such assilicaalumina and silica-magnesia form a substantial portion of thecatalyst because they have proven through past commercial experience topossess good cracking catalyst properties. In general, the compositecrystalline zeolitic catalysts comprise from about I to 25 percentzeolite, 10 to 50 percent alumina, and the remainder silica:

The zeolitic catalysts which form the high activity component of thecatalyst composition are natural or synthetic alkali metal crystallinealuminosilicates which have been treated to replace all or at least asubstantial portion of the original alkali metal ions with other cationssuch as hydrogen and/or a metal or combination of metals such as barium,calcium, magnesium, mangenese or rare earths (e.g. cerium, lanthanum,neodymium, praseodymium, samarium and yttrium). The zeolitescontemplated above may be represented by the formula M ,,,O:Al O :xSiO:yl-I5O where M represents hydrogen or a metal, n its valence, x has avalue ranging from 1 to 10 and y ranges from 0 to 10. In dehydratedzeolites, ywillbe substantially zero. In the instant invention, thepreferred zeolites contemplated are either natural or synthetic zeolitesrepresented by faujasite, zeolite X, zeolite Y, and mordenite. In highlypreferred embodiments M is selected from the group consisting ofhydrogen, calcium, manganese and the rare earth metals.

Briefly, known processes for preparing crystalline aluminosilicatesinvolve heating in an aqueous solution an appropriate mixture of oxidesor materials whose chemical composition can be completely representedas' a 'mixture of the oxides Na O, A1 SiO and H 0, at a temperatureranging from 25C. to 125C. for periods of minutes to 90 hours or more.The product which crystallizeswithin this mixture is separated andwaterwashed until the water in equilibrium with the crystalline zeolitehas a pH ranging from 9 to 12 and is thereafter dehydrated by heating.Typically, an alkali metal silicate serves as the source of silica andan alkali metal aluminate as the source of alumina. An alkali metalhydroxide is suitably used as the source of the alkali metal ion and inaddition contributes to the regulation' of the pH. The alkali metalportion is thereafter base exchanged until substantially free of alkalimetal with a solution characterized by a pH in excess of 4.5 andcontainingan ion capable of replacing the alkali metal such=as byexchanging with aqueous solutions of ammonium chloride and/or rare earthchlorides. Anions introduced as a result of treating ion-exchangesolution'are'removed by water washing. The crystalline alkali metalaluminosilicate may be ion-exchanged either before or after admixingwith a siliceous gel matrix material. The metal aluminosilicate isintimately admixed with a siliceous gel by methods such as ball millingthe aluminosilicate with a siliceous hydrogel over an extended timeperiod or by dispersing powdered aluminosilicate in a siliceoushydrosol. The siliceous gel employed'can be prepared from a naturalclay, from silica gel or from a cogel of silica and an oxide of at leastone metal from Groups lIA, IIIB and IVA of the Periodic Table. Thematerial is thereafter dried at 150 to 600F. for 4 to 48 hours. Tofurther facilitate drying, calcination at temperatures of 800F. orhigher for l to 48 hours in an inert atmosphere was optionally proposed.Finally, the prior art treatments directed that a mild steam treatmentfor catalyst activation and selectivity be undertaken at a temperaturerange of l000-l400F. for 2 to I00 hours. Temperaturesabove 1500F. weresuggested as detrimental and were to be avoided.

It has been unexpectedly found that a final treatment at temperatu resranging from above about 1300F. to about below the thermal destructiontemperature of the'zeolitic material, preferably between l400 andl550F., in the absence of steam provides the zeolitic compositedcatalyst with higher activity, selectivity and attrition resistance thanheretofore available. Some zeolitic composited catalysts contain morethermally stable zeolites and can be heat treated at temperatures inexcess of 1700F. to obtain the above catalyst improveme'nts. Theimproved catalytic properties are realized albeit that the surface areaof the zeolite containing catalyst is concommitantly reduced in manyinstances by 50% or more. Also, the quantity of zeolite in the catalystis generally reduced by this heat treatment as indicated in Table IIbelow while the activity of the catalyst increases. It appears thatactivity and surface area are independent variables, within theoperative'temperature range, such that at given surface areas, widelydivergent activities are obtainable.

In the Example I, Table III comparisons between surface area, heattreatment temperature and activity demonstrate that as the surface areaof a commercially available zeolitic catalyst is decreased from abput353 square meters per gram to about 175 square meters per gram underprogressively higherheat treating temperatures, the catalyst activitymeasured at about 33.5 rapidly maximizes to 62.4 at a temperature ofl480F. and thereafter sharply declines to 43.l at l6 50F. Above 1 650F.,further reduction of surface area closely correlates withcatalystactivity. In comparison, normal treating temperaturesconventionally used in the art of about l200 to l300F. show an activityof about 40 to 42. For purposes of comparison a conventional catalyticcracking catalyst such as UOP high alumina, UOP low alumina, Davisonhigh alumina, Davison low alumina, Nalco high alumina, Nalco lowalumina, American Cyanamid high alumina, American Cyanamid low aluminaand Filtrol when exposed to heat treatment temperatures over the rangeof 1,000 to l600F. and higher demonstrated that as the surface area ofthe catalyst decreased so did the activity. It was therefore totallyunexpected that the surface area though decreasing with the crystallinezeolitic content would provide an activity in direct opposition to thatwhich might otherwise have been predicted. Likewise, as more fullypresented in the examples below the selectivity and attrition resistanceof the catalytic material contemplated herein are substantially improvedby the heat treatment at the temperatures prescribed above. The heattreatment has been found to be effective not only when pretreating thecatalyst immediately prior to actual use but such treatment has beenfound to possess long term effects, i.e., the treatment maybe.undertaken by a catalyst manufacturer and the catalyst stored for anextended periods of time without reduction of the properties describedherein.

For the purpose of more fully illustrating the nature of our inventionand the unexpected results gained therefrom the following examples arepresented.

The catalysts below were evaluated for activity and selectivity with agas oil from North Texas Special Crude having the followingcharacteristics:

. TABLE I Fresh Charge Stock Properties Gravity, API 36.7 Pour Point, F.20

X-ray sulfur, weight 0.08

Bromine Number 3 Conradson carbon The fresh catalyst employed in thefluidized bed catalytic cracking experiments conducted wereallcommercially available materials as tabulated and identified below. Thetabulated properties correspond to-and represent the materialsevaluated. In the course of evaluation and'testing thr'ee different lotsof catalyst A and Catalyst D were employed.

TABLE 11 Catalyst A B C 1 D E F G H Properties Surface area, 353 499 591327 321 279 216 506 m lgm Pore volume, 0.72 0.76 0.66 0.77 0.56 0.580.53 0.89

cc/gm Sodium, weight 0.04 0.09 0.07 0.02 0.02 0.015 0.03 0.07

percent 1 Alumina, weight 34.1 14 16.2 32.4 27.2 34.9 16.1 14.7

percent Zeolite content 18 19 5 3 5 l 1 13 6 weight percent Zeolitecontent, 11 8 5 3 1 5 4 weight percent after 17 hours at 1480F. Cerium,weight 2.0 3.4 0.98 0.48 0.46 0.91 1.1 0.02

percent Lanthanum, weight 0.93 1.2 0.25 0.13 0.13 0.32 0.34 0.02

percent Catal sts A throu h H identified above were each y g EXAMPLE 1dried and adsorbed water removed by heating initially at 300F.,thereafter at 800F. for 1 hour and finally at 1,000F. for 2 hours. Afterthis drying period the catalyst was subjected to the desired heattreatment for In this experiment Catalyst A, untreated, was compared tosamples hea; treated at progressively higher temperatures with thresults tabulated in Table 111.

TABLE III Heat Treatment time, hours 17 17 temperature. F. 1200 1300Tests Surface area, mlgm 353 306 281 Pore volume, cc/gm 0.72 0.73Results Activity 33.5 40.2 42.6 Conversion Vol.% Feed 54.8 59.7 60.0Naphtha, Vol.% Feed 22.1 25.9 29.0 Naphtha/conversion 0.40 0.44 0.48ratio varying specified periods of time and subsequently evaluated foractivity, selectivity and attrition resistance more fully describedbelow.

The catalysts A through H for purposes of .comparison were alsosubjected to an initial drying treatment as described above along with asubsequent steam treatment consisting of exposing the'catalyst attemperatures ranging from 900 to 1150F. and pressures from 0 to 150p.s.i. g. under steam velocities ranging from 0.03 to 0.3 fps forvarying periods of time.

The tests for catalytic activity consisted of employing 400 grams ofcatalyst under the following test conditions:

Reactor Temperature, F. 920 Space Velocity, W /hr/W 2.0 Weight ratio:catalyst/oil 1.0 Reaction time, hr 0.5

The activity was measured by fractionating the cracked liquid product toa 390F. cut point. The activity is calculated as 100 minus the volumepercent gas oil above 390F. recovered from the fractionator. Theselectivity of the catalyst is the volume percent of naphtha yielddivided by the conversion. Conversion is calculated as 100 minus thevolume percent gas oil above 390F. basis total feed. The attrition ofthe catalyst is reported as 100 times the sum of the percent fines inthe attrited sample minus the percentfines in the original divided by100 minus the percent finesin the original.

As can be seen from the data in Table lllQincreasing 40 heat treatmenttemperatures correspondingly cause a decreasing catalytic surface area.\However, as the treating temperature was raised step wise, particularlyabove 1300F.', the catalytic activity rapidly increased until optimumactivity occurred between 1400 and 1600F., with highest performancebetween 1480 and 1525F. At treating temperatures above 1650F. catalystactivity rapidly decreased to below that of the untreated sample. Fromthe data presented above it appears that a transformation occurred inthe catalytic material during progressive heat treating which providedthe catalyst with enhanced activity and selectivity. From the above itwas concluded that within -t he designated temperature range catalystactivity operates independently of catalyst surface area. Treatment attemperatures above 0F. appear to destroy thefzjeolites crystallinestructure such that the treated catalyst thereafter behaves as aconventional silica alumina cracking catalyst. Moreover, the heattreated molecular sieve catalysts gave a lower carbon and gas yieldsthan conventional catalyst providing enhanced selectivity(naphtha/conversion ratio) as can be seen from the table. Theselectivity data presented demonstrate that as treating temperatureincreases within the designated temperature range naphtha volume percentfeed increases along with the naphtha/conversion ratio.

Similar treatment of catalyst B showed substantially the same resultwhen exposed to the temperatures tabulated below: i

TABLE IV Heat Treatment time, hours l7 17 17 temperature, F. 1480 16001700 Tests Surface area, mlgm 508 262 224 53 Activity 39 62.3 62.9 21.4

EXAMPLE ll Catalyst C was employed in the following tests comparing theeffects of untreated catalyst (C) with heat treated catalyst (C), withsteam treated catalyst (C and steam and heat treated catalyst (C Thesteam and heat treatments employed are shown in Table V.

'rial was further heat treated for 17 hours at 1480F.

whereupon the activity increased to 57 while the surface area wasfurther reduced to 157 m lgm.

EXAMPLE V The rate of attrition defined as:

100 [(Weight percent fines in attrited sample) (weight percent fines inoriginal sample)] 100 Weight percent fines in original sample TABLE VCatalyst C c 4 was determined on catalysts A and The attrition test I Iemployed 1S essentially as described in Ind. Eng. Chem. w steam 221 Hem2O 41, 1200 (1949) while utilizing the micromesh sieve hours 3 y 17 17technique, described in Petroleum Refiner Vol. 40, No. 'gemperature, F.1115560 1480F. 1480F. 10, pp. 139-144 (1961 to determine the finescontent.

ressure, psig Vdocityy FPS 0.1 The Table below summarizes the results.Tests TABLE VI Surface area, mlgm 591 155 130 390 Activity 46.1 42.5 4959 Catalyst A D l I Heat Treatment Conditions 1 Time, Hours None 17 None17 A similar experiment was repeated with a batch of Temp. F. 1480 V1480 catalyst D where the material had an initial surface area one Ammm2 Test Results of 327 m lgm and an activity of 35. After steam treat-Aumkmvmzo micron 256 189 151) 12,3 ment the surface area decreased to117 mlgm and the Attrition, 040 micron activity diminished to 3 1.Subsequent heat treatment of the steamed sample further decreased thesurface area to 1 l0 mlgm while the activity increased to 37.5.

- EXAMPLE lIl Catalyst E was similarly treated as in Example 11 wherethe material had an initial surface area of 321 mlg'm and an activity of37.3. After heat treatment at 1480F. for 3 hours the surface areadiminished to 205 m?/ gm while its activity increased to 43.5. Steamtreatment of the initial material at 1150F. and 150 psig for 3 hoursreduced the surface area to 90 mlgm and severely reduced the activity to23." Evaluation of catalyst G possessing an initial surface area of 216mlgm EXAMPLE V1 Table -Vll below demonstrates the heat treatment, withinthe presecribed temperature range, additionally significantly improvesthe selectivity of the catalytic material. High naphtha/conversionratios and lower coke/conversion ratios were obtained with heat treatedv TABLE vu Catalyst A D F Heat Treatment Conditions Time, Hours None 17None 17 None 17 Temp, F. 148 480 1480 Tests Activity 34.]. 58.4 32.053.0 30.9 47 .9 Na htha/conversion ratio 0.42 0.58. 0.37 0.63 0.42 0.61Co e/conversion ratio 0.094 0.061 0.078 0.029

and an activity of 42.9 was similarly steam and heat treated as catalystE. After heat treatment the catalyst had a surface area of 200 and anactivity of 50.6. Steam treatment of the initial material reduced thesurface area to 122 mlgm and the activity to 38.2.

EXAMPLE 1V A different batch of catalyst A having an initial surfacearea of 350 m'lgm was initially heat treated for 17 hours at 1480F. Thesurface area of the material dicatalysts. In this example, yet anotherbatch of catalyst- A was employed.

9 TABLE VI litic crystalline aluminosilicate and from about 99 to 7weight percent of a catalytically active siliceous matrii Heat 6. Aprocess according to claim wherein said catz Time, hours i7 3 lyticallyactive siliceous matrix is a synthetic, semisyr p ure, F. 1480 1725 5thetic or natural clay-type silica-alumina. 2%: area m m 506 262 100 Aprocess according to claim wherein said cat: Activity g 43.8 623 662lytically actlve siliceous matrix is silica-mangensla.Naphthalconversion .42 .755 .799 8. An improved catalytic crackingcatalyst compri:

ing a zeolitic crystalline aluminosilicate in a siliceou matrix, saidcatalyst characterized by enhanced actii EXAMPLE VIII ity, selectivityand attrition resistance, the improve Another batch of catalyst D washeat treated at ment of which comprises heat treating said catalyst at1600F. for varying periods of time to demonstrate the tempetature.aboveabout 1300 and i i the effect of heat exposure time on catalyst activityand mal destructive temperature of said zeol1t1c crystallin selectivity.Table IX tabulates the results obtained. alummosihqate contamed iherem mthe absence steam, said improvement being performed on a catalys TABLEIX previously rendered catalytically active by a proces comprisingdrying and calcining.

9. A catalyst according to claim 8 wherein said treat Heat TreatmentTime, minutes 15 30 60 180 Temperature, F 1700 600 1600 1600 mg 18conducted at a temperature of from about 140C Tests to about 1550 F.Activity 34.4 47.0 46.8 48.7 49.4 10. A catalyst according to claim 8wherein the zec 1 TIaPhIhK/COnverslon litic crystalline aluminosilicateis selected from th group consisting of faujasite, zeolite X, zeolite Yan mordenite.

The above results demonstrate that short exposure 11, A catalystaccording to l i 10 h i i times may be used to provide a catalyst withimp zeolitic crystalline aluminosilicate contains cation activity andselectivity. In general, when higher treating selected from the groupconsisting of hydrogen, bai temperature are employed, that is, up to thethermal ium, calcium, magnesium, manganese, rare earths me destructivetemperature of zeolitic component of the als and combinations thereof.contemplated catalytic cracking catalyst, shorter expo- 12. A catalystaccording to claim 8 wherein sai sure times are permissible. While theaforementioned catalyst comprises from about 1 to 25 weight percerexamples demonstrated exposure times ranging from zeolitic crystallinealuminosilicate and from about 9 15 minutes to 17 hours, shorter andlonger periods may to 75 weight percent of a catalytically activesiliceou be employed. While effective treating temperatures of 5 matfiX-from 1300F. up to the thermal destructive tempera- A catalyst accordingto Claim 12 wherein sai ture of the zeolite contained in the catalysthas been y y active siliceous ff is a slfnthetic 56m demonstrated to beapplicable, we prefer to employ Synthetic or natural f yp temperature offrom l400 to 1500F. In general, and

y P fQ to f f whel'em depending upon the zeolite contained in thecatalyst catalytlcany active slllceofls slhca'm?gnesla thermaldestructive temperatures occur at about Process Preparmg a catalynccrackmg and higher lyst which comprlsesn we claim, I a. calcining amaterial comprising zeolitic crystallin l. A process of increasing thecatalytic cracking acalummoslhcate"? a a at a temper 5 tivity,selectivity and attrition resistance of a catalytic P 1300 rendenng Saidmaterial cataly cracking catalyst comprising a zeolitic crystalline alubg ii i ial in the abs f t t minosilicate in a siliceous matrix, saidcatalyst having s: gigf g 3: about 33 25 223;: been renderedcatalytically active previously by a prop cess comprising drying andcalcining which comprises thermal. destruqtwe. .temperature of sadZeoht] h crystalline aluminos1licate.

eat treating said catalyst at a temperature above about a 16. A processaccording to claim 15 wherein th 1300 and Pi the thermal temperaturetemperature in step (b)'is about l400 to about l550l of said zeoliticcrystalline aluminosilicate contained h h b f 17. A process according toclaim 15 wherein tl. t erem t e a Sence, 0 zeolitic crystallinealuminosilicate is selected from th 2. A process according to claim 1wherein said treating is conducted at a temperature of from about l400group consisting of faujasite zeolite zeolite Y an o mordenite. to about1550 18. A catalytic cracking catalyst prepared by ti 3. A processaccording to claim 1 wherein the zeolitic method of claim crystallinealuminosilicate is selected from the group A catalytic cracking catalystprepared by t} consisting of faujasite, zeolite X, zeolite Y andmordenmethod f claim 16 20. A catalytic cracking catalyst prepared by ti4. A process according to claim 3 wherein said zeoth d of claim 17 litecrystalline aluminosilicate contains cations selected 21, A process ofpreparing a catalytic ki t. from the group consisting of hydrogen,barium, call hi h p ises; cium, magnesium, manganese, rare earths andcombia. calcining a material comprising zeolitic crystallir nationsthereof. aluminosilicate in a siliceous matrix at a temper 5. A processaccording to claim 1 wherein said catature below about l300F. renderingsaid materi lyst comprises from about 1 to 25 weight percentzeocatalytically active,

. .s amwwd,

group consisting of faujasite, zeolite X, zeolite Y and mordenite.

24. A catalytic cracking catalyst prepared by the method of claim 21.

25. A catalytic cracking catalyst prepared by the method of claim 22.

26. A catalytic cracking catalyst prepared by the method of claim 23.

1. A PROCESS OF INCREASING THE CATALYTIC CRACKING ACTIVITY, SELECTIVELY AND ATTRITION RESISTANCE OF A CATALYTIC CRACKING CATALYST COMPRISING A ZEOLITIC CRYSTALLINE ALUMINOSILICATE IN A SILICEOUS MATRIX, SAID CATALYST HAVING BEEN RENDERED CATALYTICALLY ACTIVE PREVIOUSLY BY A PROCESS COMPRISING DRYING AND CALCINING, WHICH COMPRISES HEAT TREATING SAID CATALYST AT A TEMPERATURE ABOVE 1300*F. AND BELOW THE THERMAL DESTRUCTIVE TEMPERATURE OF SAID ZEOLITIC CRYSTALLINE ALUMINOSILICATE CONTAINED THEREIN IN THE ABSENCE OF STEAM.
 2. A process according to claim 1 wherein said treating is conducted at a temperature of from about 1400* to about 1550*F.
 3. A process according to claim 1 wherein the zeolitic crystalline aluminosilicate is selected from the group consisting of faujasite, zeolite X, zeolite Y and mordenite.
 4. A process according to claim 3 wherein said zeolite crystalline aluminosilicate contains cations selected from the group consisting of hydrogen, barium, calcium, magnesium, manganese, rare earths and combinations thereof.
 5. A process according to claim 1 wherein said catalyst comprises from about 1 to 25 weight percent zeolitic crystalline aluminosilicate and from about 99 to 75 weight percent of a catalytically active siliceous matrix.
 6. A process according to claim 5 wherein said catalytically active siliceous matrix is a synthetic, semisynthetic or natural clay-type silica-alumina.
 7. A process according to claim 5 wherein said catalytically active siliceous matrix is silica-mangensia.
 8. An improved catalytic cracking catalyst comprising a zeolitic crystalline aluminosilicate in a siliceous matrix, said catalyst characterized by enhanced activity, selectivity and attrition resistance, the improvement of which comprises heat treating said catalyst at a temperature above about 1300*F. and below the thermal destructive temperature of said zeolitic crystalline aluminosilicate contained therein in the absence of steam, said improvement being performed on a catalyst previously rendered catalytically active by a process comprising drying and calcining.
 9. A catalyst according to claim 8 wherein said treating is conducted at a temperature of from about 1400* to about 1550*F.
 10. A catalyst according to claim 8 wherein the zeolitic crystalline aluminosilicate is selected from the group consisting of faujasite, zeolite X, zeolite Y and mordenite.
 11. A catalyst according to claim 10 wherein said zeolitic crystalline aluminosilicate contains cations selected from the group consisting of hydrogen, barium, calcium, magnesium, manganese, rare earths metals and combinations thereof.
 12. A catalyst according to claim 8 wherein said catalyst comprises from about 1 to 25 weight percent zeolitic crystalline aluminosilicate and from about 99 to 75 weight percent of a catalytically active siliceous matrix.
 13. A catalyst according to claim 12 wherein said catalytically active siliceous matrix is a synthetic semi-synthetic or natural clay-type silica-alumina.
 14. A catalyst according to claim 12 wherein said catalytically active siliceous matrix is silica-magnesia.
 15. A process of preparing a catalytic cracking catalyst which comprises: a. calcining a material comprising zeolitic crystalline aluminosilicate in a siliceous matrix at a temperature below 1300*F. rendering said material catalytically active, and b. heating said material in the absence of steam at a temperature above about 1300*F. and below the thermal destructive temperature of said zeolitic crystalline aluminosilicate.
 16. A process according to claim 15 wherein the temperatUre in step (b) is about 1400* to about 1550*F.
 17. A process according to claim 15 wherein the zeolitic crystalline aluminosilicate is selected from the group consisting of faujasite, zeolite X, zeolite Y and mordenite.
 18. A catalytic cracking catalyst prepared by the method of claim
 15. 19. A catalytic cracking catalyst prepared by the method of claim
 16. 20. A catalytic cracking catalyst prepared by the method of claim
 17. 21. A PROCESS OF PREPARING A CATALYTIC CRACKING CATALYST WHICH COMPRISES: A. CALCINING A MATERIAL COMPRISING ZEOLITIC CRYSTALLINE ALUMINOSILICATE IN A SILICEOUS MATRIX AT A TEMPERATURE BELOW ABOUT 1300*F. RENDERING SAID MATERIAL CATALYTICALLY ACTIVE, B. HEATING SAID MATERIAL IN THE PRESENCE OF STREAM AT A TEMPERATURE OF 1000* TO 1400*F., AND C. HEATING SAID MATERIAL IN THE ABSENCE OF STREAM AT A TEMPERATURE ABOVE ABOUT 1300*F. AND BELOW THE THERMAL DESTRUCTION TEMPERATURE OF SAID ZEOLITIC CRYSTALLINE ALUMINOSILICATE.
 22. A process according to claim 21 wherein the temperature of step (c) is about 1400* to about 1550*F.
 23. A process according to claim 21 wherein the zeolitic crystalline aluminosilicate is selected from the group consisting of faujasite, zeolite X, zeolite Y and mordenite.
 24. A catalytic cracking catalyst prepared by the method of claim
 21. 25. A catalytic cracking catalyst prepared by the method of claim
 22. 26. A catalytic cracking catalyst prepared by the method of claim
 23. 